Finding equation of normal to a curve.

Well I got this question:

Differentiate from first principals (i did it)

Find the equation of the normal to the curve at point where x = 3.

So first I found y. That means we got

Then I subbed 3 into to get the gradient of the tangent. Answer is

Since the normal and tangent are perpendicular the formula is So that makes

Then I subbed it into

Finally I get

but for some reason the answers in the book says it's different :(

Did I do anything wrong?

Also, I need help with another question:

If find the derivative and find the values of y when

How would I go about starting this one?